TWI692998B - Hot-pressed tin soldered circuit board and manufacturing method thereof - Google Patents

Abstract

A method for manufacturing a hot-pressed tin soldered circuit board, comprising the steps of: providing a semi-finished product of a flexible circuit board, the semi-finished product of the flexible circuit board comprising a first base layer, a first conductive circuit layer and a second copper layer, and a first plating layer formed outside of the second copper layer, the first conductive circuit layer is electrically connected to the second copper layer; the first plating layer is etched to obtain at least one stepped layer; and the second copper layer is etched to form a second conductive circuit layer, thereby obtaining a flexible circuit board, at least one solder pad is etched on the second conductive circuit layer at the position opposite to at least one stepped layer, and the size of the solder pad is larger than the size of the stepped layer to leave a tin-storing space on both sides of the solder pad; and the solder paste is printed on the stepped layer; and bonding the flexible circuit board to another circuit board, and performing reflow soldering by pulse heating to melt and cool the solder paste, forming a solde layer on the stepped layer and the solder pad, fixing and conducting the flexible circuit board and the other circuit board. The invention also provides a hot-pressed tin soldered circuit board.

Description

Hot-pressed molten tin welding circuit board and manufacturing method thereof

The invention relates to a circuit board and a manufacturing method thereof, in particular to a hot-pressed molten solder circuit board and a manufacturing method thereof.

In recent years, electronic products have been widely used in daily work and life, and the demand for miniaturization, multifunctionalization and high performance has been increasing. The density and precision of board-to-board connection are getting higher and higher. At present, the board-to-board connection is carried out by a stacked structure of hot-press soldering. The principle of hot-press melt soldering is to first print the solder paste on the pad of the circuit board, melt the solder paste after the reflow furnace and solder it to the circuit board in advance, and then place the object to be soldered on the solder paste On the circuit board, the heat of the thermal head is then used to melt the solder and connect the two electronic components that need to be connected. However, the stacking design method of hot-press melt soldering currently used is increasingly showing its limitations. For example, when hot-press melt soldering, solder paste must overflow to both sides of the pad. When the pad spacing is reduced, the pad The increased risk of short-circuits between circuits limits the reduction of the pad pitch for hot-press soldering.

In view of this, it is necessary to provide a method for manufacturing a hot-pressed solder soldering circuit board that can solve the above problems.

Also provided is a hot-pressed molten solder circuit board manufactured by the above manufacturing method.

A method for manufacturing a hot-pressed molten solder circuit board includes the following steps: providing a semi-finished product of a flexible circuit board, the semi-finished product of the flexible circuit board includes a first base layer, two opposing formed on the first base layer A first conductive circuit layer and a second copper layer on the surface, and a first electroplating layer formed outside the second copper layer, the first conductive circuit layer and the second copper layer are electrically connected; etching the first At least one step layer is obtained by an electroplating layer; the second copper layer is etched to form a second conductive circuit layer to obtain a flexible circuit board, and at least one solder is etched on the second conductive circuit layer relative to the at least one step layer Pad, the size of the pad is larger than the size of the stepped layer to leave tin overflow spaces on both sides of the pad; printing solder paste on the stepped layer; and the flexible circuit board and another The circuit board is bonded and reflow soldered by pulse heating to melt and cool the solder paste to form a solder layer on the stepped layer and the solder pad to fix and conduct the flexible circuit board to the other circuit board .

A hot-pressed molten solder circuit board includes: a flexible circuit board, the flexible circuit board includes a first base layer, a first conductive circuit layer formed on two opposite surfaces of the first base layer and electrically connected to each other Electrically connected to a second conductive circuit layer and a first electroplated layer covering the surface of the second conductive circuit layer, the first conductive circuit layer is electrically connected to the second conductive circuit layer, and is formed on the first electroplated layer There is at least one stepped layer, at least one pad is formed on the second conductive circuit layer relative to the at least one stepped layer, the size of the pad is larger than that of the stepped layer; and the flexible circuit board Another circuit board that is fixed and conducting; and a soldering layer, the soldering layer is wrapped around the stepped layer and partially contacts the solder pad to fix the flexible circuit board and the other circuit board.

In the hot-pressed molten solder circuit board of the present invention, by adding a stepped layer on the solder pad and leaving a tin overflow space on the solder pad, the solder paste rarely overflows the solder pad or will not overflow into the solder during pulse heating reflow soldering Outside the pad, the spacing between the pads can be reduced, and the design density of the hot-pressed soldering circuit board can be increased to meet the design requirements of precision products. At the same time, the first pad and the second conductive block are used to conduct heat during the hot-pressed soldering process on the solder pad, and the thermal conductivity is improved, thereby reducing the temperature of the hot-pressed soldering process.

The technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments.

Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

All technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terminology used in the description of the present invention herein is for the purpose of describing specific embodiments, and is not intended to limit the present invention.

Please refer to FIG. 1 to FIG. 11, the manufacturing method of the hot-pressed solder circuit board 100 in the first embodiment of the present invention includes the following steps:

Step S1, please refer to FIG. 1, a first substrate 10 is provided. The first substrate 10 includes a flexible first base layer 11 and first copper layers formed on opposite surfaces of the first base layer 11 respectively 13与第二铜层15。 15. The second copper layer 15.

The material of the first base layer 11 may be selected from polyimide (PI), liquid crystal polymer (LCP), polyetheretherketone (PEEK), polyethylene terephthalate Ester (Polyethylene Terephthalate, PET) and polyethylene naphthalate (Polyethylene Naphthalate, PEN) and so on.

Step S2, please refer to FIG. 2, a hole-making process is performed on the first substrate 10, and at least one first capacitor is formed on the first substrate 10 along the lamination direction of the first copper layer 13, the first base layer 11 and the second copper layer 15 Perforated 16. The first accommodating hole 16 is a blind hole, which penetrates the first copper layer 13 and the first base layer 11.

In this embodiment, the first accommodating hole 16 is formed by laser. In other embodiments, the first receiving hole 16 may be formed by other methods, such as mechanical drilling, stamping and forming.

Step S3, referring to FIG. 3, the first accommodating hole 16 is plated and filled to form a first conductive block 17, so that the first copper layer 13 and the second copper layer 15 are electrically connected.

The first conductive block 17 may be copper, silver, tin, gold, or other conductive metal materials.

The first conductive block 17 may have any shape such as a cylindrical shape, a truncated cone shape, and a rectangular parallelepiped shape. In this embodiment, the first conductive block 17 has a truncated cone shape, and the first end of the first conductive block 17 having a larger diameter is connected to the surface of the first copper layer 13.

Step S4, please refer to FIG. 4, the first copper layer 13 is etched to form a first conductive circuit layer 130, and a second layer is pressed on the surface of the first conductive circuit layer 130 facing away from the first base layer 11 by a glue layer 30 The substrate 20. The second substrate 20 includes a flexible second base layer 21 pressed onto the surface of the adhesive layer 30 and a third copper layer 23 formed on the surface of the second base layer 21. The material of the second base layer 21 is the same as the material of the first base layer 11.

In this embodiment, the material of the adhesive layer 30 is a resin with viscosity. More specifically, the resin may be selected from polypropylene, epoxy resin, polyurethane, phenol resin, urea resin, melamine-formaldehyde resin and poly At least one of amide imine and the like.

Step S5, please refer to FIG. 5, a hole-making process is performed on the position of the second substrate 20 relative to the first conductive block 17, and the third copper layer 23, the second base layer 21 and the adhesive layer 30 are stacked on the second substrate 20 At least one second receiving hole 26 is opened in the direction. The second accommodating hole 26 is a blind hole, which penetrates the third copper layer 23, the second base layer 21 and the adhesive layer 30 and exposes the first conductive block 17.

Step S6, please refer to FIG. 6, electroplating the surfaces of the first substrate 10 and the second substrate 20, a first plating layer 19 is formed outside the second copper layer 15, and a second layer is formed outside the third copper layer 23 An electroplating layer 29 is electroplated to fill the second accommodating hole 26 to form a second conductive block 27 to obtain a semi-finished flexible circuit board. The second conductive block 27 electrically connects the third copper layer 23 and the first conductive circuit layer 130. In this embodiment, copper plating is performed on the surfaces of the first substrate 10 and the second substrate 20. Understandably, in other embodiments, silver, tin, gold, etc. may be plated on the surfaces of the first substrate 10 and the second substrate 20. metallic material.

Step S7, referring to FIG. 7, the first plating layer 19 and the second plating layer 29 are partially etched, and at least one step layer 191 is etched on the first plating layer 19 relative to the first conductive block 17.

Wherein, the thickness of the step layer 191 is greater than 15 μm.

In this embodiment, the stepped layer 191 is etched by the first electroplating layer 19. In other embodiments, the stepped layer 191 may also be a thicker second copper layer exposed after the first electroplated layer 19 is etched 15 Partially etched.

Step S8, referring to FIG. 8, developing, etching, and stripping (Developing Etching Stripping, DES) processes are performed on the first substrate 10 and the second substrate 20 to form the second copper layer 15 into the second conductive circuit layer 150, The third copper layer 23 is formed into a third conductive circuit layer 230 to obtain a flexible circuit board 40. At least one pad 151 is etched on the second conductive circuit layer 150 at a position relative to at least one stepped layer 191.

The stepped layer 191 on the pad 151 is located in the center of the pad 151 and the size of the stepped layer 191 is smaller than that of the pad 151 so as to leave a tin overflow space 152 on both sides of the pad 151. The size of the overflow tin space 152 is greater than 35 μm.

Step S9, please refer to FIG. 9, a solder mask is printed on the second conductive circuit layer 150 and the third conductive circuit layer 230 to form a protective layer 50. The protective layer 50 covers the surfaces of the second conductive circuit layer 150 and the third conductive circuit layer 230, fills the gaps on the surfaces of the second conductive circuit layer 150 and the third conductive circuit layer 230, and exposes the second conductive circuit layer 150 of the pad 151 and the stepped layer 191 thereon. In this embodiment, the protective layer 50 may be a solder mask or a cover layer (CVL) commonly used in the industry.

In step S10, referring to FIG. 10, a solder paste 60 is printed on the step layer 191.

Step S11, please refer to FIG. 11, the flexible circuit board 40 is bonded to another circuit board 70, and reflow soldering is performed by pulse heating, so that the solder paste 60 on the step layer 191 is melted and cooled. A solder layer 61 is formed on the solder pad 151 to fix and conduct the flexible circuit board 40 to another circuit board 70.

During soldering and reflow soldering, the solder paste 60 melts and partially flows into the solder overflow space 152. The solder paste 60 rarely overflows the solder pad 151 or does not overflow the solder pad 151.

Referring to FIG. 12, the second embodiment of the present invention provides a method for manufacturing a hot-pressed soldered circuit board 100, which differs from the method for manufacturing a hot-pressed soldered circuit board 100 in the first embodiment in that: After step S1, step S4 is performed, and then step S2 and step S5 are simultaneously performed, and the first accommodating hole 16 formed in step S2 penetrates the second copper layer 15 and the first base layer 11, in step S5 , The formed second accommodating hole 26 penetrates through the third copper layer 23, the second base layer 21 and the adhesive layer 30 and exposes the first conductive circuit layer 130, the first accommodating hole 16 and the first The two receiving holes 26 are relatively opened. Subsequently, steps S3 and S6 are simultaneously performed, and then steps S7 to S11 are sequentially performed.

Referring to FIG. 11, a preferred embodiment of the present invention further provides a hot-pressed solder circuit board 100 including a flexible circuit board 40, a protective layer 50 covering the flexible circuit board 40, a solder layer 61 and The other circuit board 70 that the flexible circuit board 40 is fixed and conducting.

The flexible circuit board 40 includes a flexible first base layer 11, a first conductive circuit layer 130 and a second conductive circuit layer 150 formed on two opposite surfaces of the first base layer 11 and electrically connected to each other, A second base layer 21 formed on the surface of the first conductive circuit layer 130 through a glue layer 30, a third conductive circuit layer 230 formed on the surface of the second base layer 21, and a first cladding coated on the surface of the second conductive circuit layer 150 The plating layer 19 and the second plating layer 29 covering the surface of the third conductive circuit layer 230.

The first conductive circuit layer 130 and the second conductive circuit layer 150 are electrically connected by at least one first conductive block 17, and the second conductive circuit layer 150 and the third conductive circuit layer 230 are electrically connected by at least one second conductive block 27 connection. The first conductive block 17 is opposite to the second conductive block 27.

At least one stepped layer 191 is formed on the first electroplated layer 19 relative to the first conductive block 17, and at least one pad 151 is formed on the second conductive circuit layer 150 relative to the at least one stepped layer 191. The solder layer 61 covers the step layer 191 and partially contacts the solder pad 151.

In the hot-pressed solder soldering circuit board 100 of the present invention, by adding a stepped layer 191 on the solder pad 151 and leaving a solder overflow space 152 on the solder pad 151, the solder paste 60 rarely overflows into the solder during pulse heating reflow soldering The pads 151 may not overflow the pads 151, so that the spacing between the pads 151 can be reduced, and the design density of the hot-pressed soldering circuit board 100 can be improved to meet the design requirements of precision products. At the same time, the first pad 17 and the second pad 27 are used to conduct heat during the hot-pressing soldering process on the pad 151, and the thermal conductivity is improved, thereby reducing the temperature of the hot-pressing soldering process.

In addition, the above is only the preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has disclosed the preferred embodiment as above, it is not intended to limit the present invention. Anyone who is familiar with this profession Technical personnel within the scope of the technical solution of the present invention, when the above disclosed technical content can be used to make some changes or modifications to equivalent equivalent implementations, but those who do not deviate from the technical solution content of the present invention, according to the present invention Any simple modifications, equivalent changes, and modifications made to the above embodiments by the technical essence of the technology still fall within the scope of the technical solutions of the present invention.

FIG. 1 is a schematic cross-sectional view of a first substrate according to a first embodiment of the invention.

FIG. 2 is a schematic cross-sectional view of openings in the first substrate shown in FIG. 1.

3 is a schematic cross-sectional view of the opening of the first substrate shown in FIG. 2 being plated and filled with holes.

4 is a schematic cross-sectional view of a second substrate pressed onto the first substrate in FIG. 3.

FIG. 5 is a schematic cross-sectional view of openings in the second substrate shown in FIG. 4.

6 is a schematic cross-sectional view of electroplating on the surfaces of the first substrate and the second substrate shown in FIG. 5.

7 is a schematic cross-sectional view of partially etching the surfaces of the first substrate and the second substrate shown in FIG. 6.

FIG. 8 is a schematic cross-sectional view of a flexible circuit board formed on the surfaces of the first substrate and the second substrate shown in FIG. 7 by development, etching, and film removal processes.

9 is a schematic cross-sectional view of performing solder mask printing on the surface of the flexible circuit board shown in FIG. 8.

FIG. 10 is a schematic cross-sectional view of printing solder paste on the surface of the stepped layer of the flexible circuit board shown in FIG. 9.

FIG. 11 is a schematic cross-sectional view of pasting the flexible circuit board shown in FIG. 10 to another circuit board and heating and reflow soldering to form a hot-pressed molten solder circuit board.

12 is a schematic cross-sectional view of a hot-pressed solder circuit board according to a second embodiment of the present invention.

no

Claims (10)

A method for manufacturing a hot-pressed solder soldered circuit board includes the following steps: providing a semi-finished product of a flexible circuit board, the semi-finished product of the flexible circuit board includes a first base layer, and two opposing formed on the first base layer A first conductive circuit layer and a second copper layer on the surface, and a first electroplating layer formed outside the second copper layer, the first conductive circuit layer and the second copper layer are electrically connected; etching the first At least one step layer is obtained by an electroplating layer; the second copper layer is etched to form a second conductive circuit layer to obtain a flexible circuit board, and at least one solder is etched on the second conductive circuit layer relative to the at least one step layer Pad, the size of the pad is larger than the size of the stepped layer to leave space for overflowing tin on both sides of the pad; printing solder paste on the stepped layer; and the flexible circuit board and another The circuit board is bonded and reflow soldered by pulse heating to melt and cool the solder paste to form a solder layer on the stepped layer and the solder pad to fix and conduct the flexible circuit board to the other circuit board . The method for manufacturing a hot-pressed soldered soldered circuit board as described in item 1 of the patent scope, wherein the size of the overflowing tin space is greater than 35 μm. The method for manufacturing a hot-pressed soldered soldering circuit board as described in item 1 of the patent scope, wherein: the thickness of the stepped layer is greater than 15 μm. The method for manufacturing a hot-pressed solder soldered circuit board as described in item 1 of the patent application scope, wherein: the semi-finished product of the flexible circuit board further includes a second base layer formed on the surface of the first conductive circuit layer and formed on the The step of obtaining the third copper layer on the surface of the second base layer to obtain the flexible circuit board further includes etching the third copper layer to form a third conductive circuit layer. The method for manufacturing a hot-pressed solder soldered circuit board as described in item 4 of the patent application scope, wherein: the step of providing the semi-finished product of the flexible circuit board includes: providing a first substrate, the first substrate including a first A base layer and a first copper layer and a second copper layer respectively formed on two opposite surfaces of the first base layer; performing a hole-making process on the first substrate and opening at least one first container on the first substrate Hole; electroplating and filling the first accommodating hole to form a first conductive block, so that the first copper layer is electrically connected to the second copper layer; etching the first copper layer to form a first conductive line Layer, and a second substrate is laminated on the surface of the first conductive circuit layer by an adhesive, the second substrate includes a second base layer and a third copper layer formed on the surface of the second base layer; Performing a hole-opening process on the position of the second substrate relative to the first conductive block, opening at least one second accommodating hole in the second substrate; performing on the surfaces of the first substrate and the second substrate Electroplating, forming a first electroplating layer outside the second copper layer, forming a second electroplating layer outside the third copper layer, electroplating filling the second accommodating hole to form a second conductive block, so that the The third copper layer is electrically connected to the first conductive circuit layer. The method for manufacturing a hot-pressed tin-solder soldered circuit board as described in item 5 of the patent scope, wherein at least one of the stepped layers etched on the second copper layer corresponds to the first conductive block. A hot-pressed molten solder circuit board includes: a flexible circuit board including a first base layer, a first conductive circuit layer formed on opposite surfaces of the first base layer and electrically connected to each other Electrically connected to a second conductive circuit layer and a first electroplated layer covering the surface of the second conductive circuit layer, the first conductive circuit layer is electrically connected to the second conductive circuit layer, and is formed on the first electroplated layer There is at least one stepped layer, at least one pad is formed on the second conductive circuit layer relative to the at least one stepped layer, the size of the pad is larger than that of the stepped layer; and the flexible circuit board Another circuit board that is fixed and conducting; and a soldering layer, the soldering layer is wrapped around the stepped layer and partially contacts the solder pad to fix the flexible circuit board and the other circuit board. The hot-press soldering circuit board as described in item 7 of the patent application scope, wherein: the flexible circuit board further includes a second base layer formed on the surface of the first conductive circuit layer through an adhesive layer and formed on the A third conductive circuit layer on the surface of the second base layer, the first conductive circuit layer and the second conductive circuit layer are electrically connected by at least one first conductive block, and the second conductive circuit layer and the third conductive circuit The layers are electrically connected by at least one second conductive block, the first conductive block is disposed opposite to the second conductive block, and at least one stepped layer is formed on the first electroplated layer relative to the first conductive block. The hot-press soldering circuit board as described in item 7 of the patent application scope, wherein: the flexible circuit board is also covered with a protective layer. The hot-pressed solder solder circuit board as described in item 7 of the patent scope, wherein: the thickness of the stepped layer is greater than 15 μm.

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